1. Field of the Invention
The invention relates to a method for preparing 3,3-dimethylbutyraldehyde as an intermediate for producing a sweetener.
2. Description of the Related Art
Neotame is a sweetener characterized by high sweetness and low cariogenicity. It has a great market potential and has been produced by different methods. However, as an important intermediate for producing the Neotame, 3,3-dimethylbutyraldehyde is relatively expensive.
A typical method for preparing 3,3-dimethylbutyraldehyde employs ethylene gas as the raw material. However, ethylene gas imposes high requirements on the transportation, storage, and production device, and risk exists in the transportation and the production process. The conventional preparation method is long and energy consuming, employs an inactive gas as a carrier to gasify a mixture of 3,3-dimethylbutyraldehyde and water at a temperature of above 300° C., and utilizes dehydrogenation in the presence of a precious metal. The method has low safety and high production cost. 3,3-dimethylbutyl chloride is expensive, and the resulting dimethyl thioethers cause environmental pollution.